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.TH PTHREAD_COND_INIT 3C "Mar 23, 2005"
.SH NAME
pthread_cond_init, pthread_cond_destroy \- initialize or destroy condition
variables
.SH SYNOPSIS
.LP
.nf
cc -mt [ \fIflag\fR... ] \fIfile\fR... -lpthread [ \fIlibrary\fR... ]
#include <pthread.h>

\fBint\fR \fBpthread_cond_init\fR(\fBpthread_cond_t *restrict\fR \fIcond\fR,
     \fBconst pthread_condattr_t *restrict\fR \fIattr\fR);
.fi

.LP
.nf
\fBint\fR \fBpthread_cond_destroy\fR(\fBpthread_cond_t *\fR\fIcond\fR
.fi

.LP
.nf
\fBpthread_cond_t\fR \fIcond\fR= \fBPTHREAD_COND_INITIALIZER\fR;
.fi

.SH DESCRIPTION
.sp
.LP
The function \fBpthread_cond_init()\fR initializes the condition variable
referenced by \fIcond\fR with attributes referenced by \fIattr\fR. If
\fIattr\fR is  \fBNULL\fR, the default condition variable attributes are used;
the effect is the same as passing the address of a default condition variable
attributes object. See \fBpthread_condattr_init\fR(3C). Upon successful
initialization, the state of the condition variable becomes initialized.
.sp
.LP
Attempting to initialize an already initialized condition variable results in
undefined behavior.
.sp
.LP
The function \fBpthread_cond_destroy()\fR destroys the given condition variable
specified by \fIcond\fR; the object becomes, in effect, uninitialized. An
implementation may cause \fBpthread_cond_destroy()\fR to set the object
referenced by \fIcond\fR to an invalid value. A destroyed condition variable
object can be re-initialized using \fBpthread_cond_init()\fR; the results of
otherwise referencing the object after it has been destroyed are undefined.
.sp
.LP
It is safe to destroy an initialized condition variable upon which no threads
are currently blocked. Attempting to destroy a condition variable upon which
other threads are currently blocked results in undefined behavior.
.sp
.LP
In cases where default condition variable attributes are appropriate, the macro
\fBPTHREAD_COND_INITIALIZER\fR can be used to initialize condition variables
that are statically allocated. The effect is equivalent to dynamic
initialization by a call to \fBpthread_cond_init()\fR with parameter \fIattr\fR
specified as  \fBNULL,\fR except that no error checks are performed.
.SH RETURN VALUES
.sp
.LP
If successful, the \fBpthread_cond_init()\fR and \fBpthread_cond_destroy()\fR
functions return  \fB0\fR. Otherwise, an error number is returned to indicate
the error. The \fBEBUSY\fR and \fBEINVAL\fR error checks, if implemented, act
as if they were performed immediately at the beginning of processing for the
function and caused an error return prior to modifying the state of the
condition variable specified by \fIcond\fR.
.SH ERRORS
.sp
.LP
The  \fBpthread_cond_init()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEAGAIN\fR\fR
.ad
.RS 10n
The system lacked the necessary resources (other than memory) to initialize
another condition variable.
.RE

.sp
.ne 2
.na
\fB\fBENOMEM\fR\fR
.ad
.RS 10n
Insufficient memory exists to initialize the condition variable.
.RE

.sp
.LP
The \fBpthread_cond_init()\fR function may fail if:
.sp
.ne 2
.na
\fB\fBEBUSY\fR\fR
.ad
.RS 10n
The implementation has detected an attempt to re-initialize the object
referenced by \fIcond\fR, a previously initialized, but not yet destroyed,
condition variable.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The value specified by \fIattr\fR is invalid.
.RE

.sp
.LP
The \fBpthread_cond_destroy()\fR function may fail if:
.sp
.ne 2
.na
\fB\fBEBUSY\fR\fR
.ad
.RS 10n
The implementation has detected an attempt to destroy the object referenced by
\fIcond\fR while it is referenced (for example, while being used in a
\fBpthread_cond_wait()\fR or \fBpthread_cond_timedwait()\fR) by another thread.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The value specified by \fIcond\fR is invalid.
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR pthread_cond_broadcast (3C),
.BR pthread_cond_signal (3C),
.BR pthread_cond_timedwait (3C),
.BR pthread_cond_wait (3C),
.BR pthread_condattr_init (3C),
.BR attributes (7),
.BR condition (7),
.BR standards (7)
